1. Field of the Invention
The present invention relates to a disk brake for use in a vehicle to brake the rotation of the axle, for example.
2. Description of Related Art
A disk brake used to brake a wheel of a vehicle has a cylinder provided on a brake caliper. A piston accommodated in a bore of the cylinder presses a brake pad against a disk in response to a fluid pressure, thereby applying a braking force to the wheel.
In one type of such a disk brake, the cylinder is divided into a bottom lid member and a tubular cylinder body having an opening that is closed with the lid member for the purpose of facilitating machining of the interior of the cylinder, for example. That is, after the interior of the cylinder body has been machined through the opening, the lid member is attached to the opening so as to close it. In this disk brake, installation of the lid member is performed as follows. An external thread formed on the outer periphery of the lid member is screwed to an internal thread formed on the inner peripheral surface of the opening of the cylinder body, thereby securing the lid member to the opening (for example, see Japanese Utility Model Application Publication No. Hei 6-69456).
In the above-described conventional disk brake, the peripheral wall of the opening of the cylinder body has an increased wall thickness to reliably support the lid member by the opening. The outer diameter of the outer peripheral wall of the bore of the cylinder body is set equal to or larger than the outer diameter of the portion of the cylinder body where the opening is formed. Therefore, it is likely that the whole cylinder body will increase in wall thickness and the overall weight of the device will increase unfavorably.